Study of fresh and hardened properties of concrete modified with recycled concrete aggregates

Abstract

The rapid urbanization and industrialization of the world in the last few decades has led to the ever rising demand of construction materials especially aggregates. Mining of these aggregates has led to a strain on the environment and in serious ecological damagae. Thus mining has been banned in some states by the government. The shortfall of construction aggregates is a serious problem and necessitates the use of other recycled aggregates as its replacement. Recycled aggregates are obtained from old demolished construction waste. Usually they are transported to a landfill site where they are disposed. The expansion of cities in the past decades has not only made landfill sites farther but also at the same time made the transportation of these aggregates costlier. The solution is to use these as a replacement for natural aggregates in concrete mixes. This has the potential to significantly reduce the need for mining new aggregates and also at the same time reduce disposing costs. This paper deals with the study of Recycled aggregate concrete with varying percentages of recycled aggregate as a replacement for natural aggregates. In addition to this, this paper also investigates the efficacy of using the ‘Ultrasonic Guided wave’ method for measuring the strength and fresh properties of concrete mixes over the more common Ultrasonic Pulse Velocity method. It will be demonstrated in the course of this work, as to what advantages the Ultrasonic Guided wave method has over other conventional methods such as the ‘Ultrasonic Pulse velocity’ method.